Induction of laccase by metal ions and aromatic compounds in Pleurotus ostreatus HAUCC 162 and decolorization of different synthetic dyes by the extracellular laccase

- Extracellular laccase activity was stimulated by metal ions or aromatic compounds.
- Synergistic stimulation by metal ions and aromatic compounds on laccase was observed.
- Transcript levels of laccase gene family under different stimulations were studied.
- The crude extracellular laccase could efficiently degrade different synthetic dyes.

Promotion of laccase production has attracted much attention, because of its potential application in environment and industry areas. Metal ions and aromatic compounds are known to be effective in stimulating laccase production in many white-rot fungi. In this study, we examined the effect of several metal ions and aromatic compounds on extracellular laccase activity as well as on the transcription of laccase multi-gene family in Pleurotus ostreatus HAUCC 162. Extracellular laccase activity is enhanced by the addition of Cu2+ (3.86-fold), Fe2+ (1.85-fold), Mn2+ (1.65-fold), Cd2+ (1.45-fold), ferulic acid (1.83-fold), vanillic acid (1.62-fold), coumaric acid (2.16-fold), and cinnamic acid (1.95-fold) after 10-days induction, and the increased transcript level of laccase multi-gene family was also observed. Synergistic stimulation of metal ions (Fe2+, Cu2+) and aromatic compounds (vanillic acid, cinnamic acid, and ferulic acid) further improved the stimulatory effect, compared with single inducer. The results of decolorization test further indicated the laccase produced by P. ostreatus HAUCC 162 had a strong capacity to decolorize different synthetic dyes, which offers an opportunity to apply P. ostreatus HAUCC 162 laccase in the field of environmental biotechnology.